In a conventional apparatus for manufacturing semiconductor wafers, the air circulating and filtering unit of the apparatus utilizes a single control electric motor to control the air flow and the pressure in the whole apparatus, thus the internal of the apparatus may not reach a high cleaning degree. Furthermore, since the apparatus generally utilizes a single-armed manipulator which processes only one wafer at a time with less degree of freedom and small covering area, the wafer transport efficiency is low. In addition, due to the uneven distribution of the chemical gas/liquid distribution unit in the apparatus, the flow and pressure in each process chamber is different, which affects the product yield rate per unit area.